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L‐Leucine Increases Skeletal Muscle IGF‐1 Peptide But Has No Effect on Akt/mTOR Signaling in Response to Resistance Exercise in Trained Men
Author(s) -
Church David,
Schwarz Neil,
Spillane Mike,
McKinley Sarah,
Andre Tom,
Stout Jeffery,
Hoffman Jay,
Willoughby Darryn
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.819.2
Subject(s) - leucine , mtorc1 , pi3k/akt/mtor pathway , protein kinase b , endocrinology , medicine , skeletal muscle , placebo , chemistry , ingestion , signal transduction , amino acid , biochemistry , pathology , alternative medicine
Background Leucine ingestion following resistance exercise (RE) increases muscle protein synthesis via mammalian target of rapamycin complex 1 (mTORC1) at a dose of 3g. It has also been shown that skeletal muscle (SM) IGF‐1 activates mTORC1. It is plausible that leucine can increase SM IGF1, elucidating another mechanism in which mTORC1 activity might be up‐regulated.
Purpose: The effect of a single threshold dose of L‐leucine given immediately after RE on serum leucine and IGF1, and SM IGF1, IGF1 receptor (IGF1R), Akt, mTOR, and p70S6K.
Methods: 9 resistance‐trained men performed two separate testing sessions of 4 sets of 8‐10 reps at 75‐80% 1‐RM on the angled leg press and knee extension exercises. Immediately after, 3g of L‐leucine (LEU) or placebo in the form of gelatin capsules was ingested. Venous blood was obtained before, 0.5‐, 2‐, and 6‐hr post‐exercise, and a muscle biopsy obtained before, 2‐ and 6‐hr post‐exercise. A repeated measures ANOVA (treatment x time) for each criterion variable was performed.
Results: Increases were noted in serum [leucine] in LEU group (p=0.04), muscle IGF1 at 2‐hr (p=0.03) and 6‐hr (p=0.04), with no changes observed in serum IGF‐1 (p=0.99), IGF‐1R (p=0.84), Akt (p=0.55), mTOR (p=0.09), and P70S6K (p=0.98).Conclusion: 3 g of L‐leucine following a RE session does not appear to influence serum [IGF1] or mTORC1 signaling, but did preferentially increase IGF1 peptide content in SM.